Insert part for foaming into foam cushion parts, preferably of vehicle or aircraft seats

ABSTRACT

In an insert part for foaming into foam cushion parts, preferably of vehicle or aircraft seats, having at least one line-shaped fixing element ( 11 ) which, partially fixed in the foam material and partially kept clear of it, is used for the application of anchoring elements for securing the position of covering materials, the fixing element ( 11 ) consists of a plastic material ( 13, 17 ) which has ferromagnetic properties or which contains ferromagnetic portions, or the fixing element ( 11 ) has an inner core ( 15 ) with ferromagnetic properties which is at least partially surrounded by a plastic jacket ( 13 ).

The invention relates to an insert part for foaming into foam cushion parts, preferably of vehicle or aircraft seats, having at least one line-shaped fixing element which, partially fixed in the foam material and partially kept clear of it, is used for the application of anchoring elements for securing the position of covering materials.

In seats, especially those for passenger transportation in motor vehicles or aircraft, for seat components such as the seat part and/or seat back and/or headrest, cushion parts are frequently used in which the core of the cushion is a shaped foam body, for example of polyurethane. In order to ensure good seat use properties, it is extremely important for the respective covering material, which can be attached to the foam cushion part as an edging and which forms the outer surface of the cushion part serving the purpose of a leaning or support surface for parts of seat occupant's body, to be suitably anchored. Attachment systems used for this purpose must ensure that reliable anchoring of the covering material is maintained even under the changing, heavy loads applied by the parts of the seat occupant's body. Known attachment systems do not adequately meet this requirement. One known solution calls for fixing elements to be foamed into the cushion part in the forming process which takes place in the pertinent foam mold, along the desired tacking lines on which the covering material is to be tacked to the cushion part, for example adhesive fastener strips being inserted into the foam mold and their assigned mold walls being shaped such that the adhesive fastener strips are foamed embedded into the grooves which form the tacking lines. Another known solution, cf. DE 39 06 200 A1, calls for attachment of retaining strips, which are fixed on the covering material, with barbs which interact with a specially designed clamp strip which is attached to the cushion part and which extend behind the barbs.

The initially referred to solution with the adhesive fastener elements laid in foam is unsatisfactory in two respects. On the one hand, a foam mold with a complex shape must be used in order to secure the adhesive fastener strips for the foaming process in the foam mold in the correctly inserted position, the foam mold at the same time having to be configured such that the interlocking elements of the adhesive fastener strips are protected against the entry of foam material. Secondly, this solution does not offer strong enough anchoring which could also withstand very high local seat loads. On the other hand, the solution disclosed in DE 39 06 200 A1 with specially shaped clamp strips on the cushion part and fitting retaining strips which are to be attached to the covering material, having barbs, is disadvantageously especially complex.

In order to avoid the aforementioned shortcomings, foaming a retaining wire into the foam material of the cushion part as a line-shaped fixing element is also known, the retaining wire being laid in foam along the tacking lines such that the retaining wire is free of foam material in sections and in these sections is accessible to the application of anchoring means on the covering material. In this solution simple magnetic fixing of an optionally ferromagnetic retaining wire in the foam mold is possible, so that the foam mold can be made comparatively simple in structure. But in order to ensure that the retaining wire is securely held by the foam material in the longitudinal sections which have been foamed into the foam material and which are located between the exposed sections such that for the loads under consideration the wire is prevented from tearing out of the foam material, only a retaining wire with a comparatively large diameter can be used. As has been found, there is specifically the danger that a thin retaining wire under loads will act as a cutting wire and will cut through the foam material. If a retaining wire of sufficiently large diameter is used, there arise the disadvantages of high weight, correspondingly high material costs, and difficult installation in the foam mold due to the stiffness which has been increased with the high wire cross section.

On the basis of this prior art, the object of the invention is to make available an insert part which overcomes the aforementioned problems.

As claimed in the invention, this object is achieved by an insert part having the features specified in claim 1 in its entirety.

In that, as specified in the characterizing part, the fixing element consists mainly of a plastic material, without having to tolerate the aforementioned disadvantages which arise when using a retaining wire, the fixing element can be given such a large outside diameter that on the outside of the fixing element a surface encompassed by the foam material is made available which is so large that especially high reliability against tearing out of the foam material is ensured. In that there is moreover a plastic material with ferromagnetic properties or the plastic material contains ferromagnetic portions, with respect to magnetic locking in position in the foam mold the same advantages arise as occur in the use of the known retaining wire in this respect, its mentioned disadvantages however not having to be tolerated.

Preferably the fixing element has the shape of a flexible plastic rod, preferably with a round cross sectional shape. In this connection the rod can contain ferromagnetic components, for example ferrite particles, or can be provided with a ferromagnetic coating.

As an alternative example, the fixing element can have a plastic tube which forms an at least almost closed casing of the inner core which has ferromagnetic properties.

In this embodiment, the fixing element can be designed as an electrical conductor wire which is jacketed with plastic insulation, that is, a single electrical cable, there being a ferromagnetic wire in place of the copper wire which normally forms the conductor.

However, as the core located within the plastic tube, in place of a normal wire a substance can also be contained which contains ferromagnetic components, for example in particle form.

Alternatively the core can be formed by a plastic strand contained with the plastic tube having ferromagnetic properties.

The invention will be detailed below using embodiments shown in the drawings in which

FIG. 1 shows a perspective, detached view of only the upper end area of the foam cushion part which explains the prior art for a seat back with molded-on head cushion part, the covering material being omitted, and a conventional retaining wire laid in foam for the anchoring elements being partially visible;

FIG. 2 shows a perspective of a fixing element according to one exemplary embodiment of the insert part of this invention,

FIG. 3 shows a perspective view of another embodiment which is similar to FIG. 2, and

FIG. 4 shows a perspective view of another embodiment which is similar to FIG. 2.

In FIG. 1 the cushion part which forms the cushion body or the cushion core of polyurethane foam is designated as 1; a head cushion part 3 is formed integrally on its upper end area. According to the prior art, in the foaming process in which the cushion part 1 together with the head cushion part 3 is shaped by means of a foam mold from polyurethane foam, between the cushion part 1 and the head cushion part 3 a channel-like groove 5 is formed which forms a tacking line along which covering material which is not shown can be tacked, i.e., attached, along the head cushion part 3. For this purpose, within the groove 5 a fixing element in the form of a conventional retaining wire is laid in foam such that the wire sections 7 are kept free of the foam material and alternate with the longitudinal sections 9 which have been laid in foam.

As already mentioned, when a retaining wire is being used in which a ferromagnetic wire, for example a steel wire, is used, it becomes possible to provide magnetic insert parts in the pertinent foam mold so that the retaining wire is positioned and fixed accordingly for the foaming process in the mold. But as likewise mentioned, the diameter of the retaining wire must be chosen to be so great that in the longitudinal sections 9 which have been laid in foam, enough surface which is foamed in place with foam material is available to prevent the retaining wire from tearing out.

FIG. 2 shows one embodiment for a fixing element 11 which is to be used as an insert part as claimed in the invention in place of the conventional retaining wire, one which has a plastic tube 13 containing a continuous ferromagnetic wire 15 as the inner core. By the corresponding dimensioning of the plastic tube 13 this execution of the fixing element 11 enables the outside diameter to be made so large that the required reliability of anchoring in the foam material of the cushion parts 1 and 3 is ensured without as a result the disadvantages of high weight and increased stiffness having to be tolerated, as is the case in the prior art when the diameter of the retaining wire is increased.

FIG. 2 shows that the ferromagnetic wire 15 forming the core extends continuously over the length of the tube 13. In this configuration the fixing element 11 can assume the additional function of an insulated electrical conductor, the wire 15 forming the electrical conductor, so that the fixing element 11 can also be used as a component of electrical accessories of the seat, for example for audio systems, ventilation means on the seat back area or head cushion area, and the like. However the wire 15 need not be continuous within the tube 13. It is sufficient for the wire 15 to extend over those longitudinal sections in which there are magnetic insert parts in the pertinent foam mold. Moreover, in place of a core formed by the wire 15, there could be a substance which is located within the plastic tube 13 and which contains ferromagnetic components, for example in particle form.

FIG. 3 shows another example in which the fixing element is formed by a rod 17 of a relatively flexible plastic. Here it can be a plastic which contains a rod of ferromagnetic components or a plastic rod which is provided with a ferromagnetic coating. In this exemplary embodiment the outside diameter of the rod 17 can be chosen to be so large that the required protection against tearing out of the foam material is ensured.

As when using a conventional retaining wire, when using a fixing element 11 as is provided as an insert part as claimed in the invention, the anchoring elements can be holding clamps for the covering material which extend behind the fixing element 11. When the fixing element 11 is being laid in foam, a foam-repellent coating, such as for example a sol-gel of the type disclosed in EP 1 082 031 B1, can be applied, for example sprayed, onto the fixing element before insertion into the foam mold in the longitudinal sections 7 which are to be kept clear of the foam material.

FIG. 4 shows another, modified embodiment of the solution as claimed in the invention. The plastic jacket 13 is provided this time with a structure in order to thus improve its effective surface for the forthcoming adhesion processes with the foam. In the exemplary embodiment shown in FIG. 4, the jacket 13 in cross section is provided with preliminary convex arches which meet adjacently along the connecting lines. Other structuring which is not detailed would be conceivable, for example in the form of concave impressions in the jacket surface. In the illustrated embodiments as shown in FIGS. 2 and 4, the impression is vividly created that the jacket 13 surrounds the wire 15 over its entire surface; but preferably the respective jacket 13 forms a type of hollow cylinder, in the hollow opening of which the wire 15 can be freely moved along definable path sections; this enhances the adaptation possibilities for the fixing element 11 in the foam material of a cushion. 

1. Insert part for foaming into foam cushion parts (1, 3), preferably of vehicle or aircraft seats, having at least one line-shaped fixing element (11) which, partially fixed in the foam material and partially kept clear of it, is used for the application of anchoring elements for securing the position of covering materials, characterized in that the fixing element (11) consists of a plastic material (13, 17) which has ferromagnetic properties or ferromagnetic portions, or that the fixing element (11) has an inner core (15) with ferromagnetic properties which is at least partially surrounded by a plastic jacket (13).
 2. The insert part as claimed in claim 1, wherein the fixing element (11) has the shape of a flexible plastic rod (17), preferably with a round cross sectional shape.
 3. The insert part as claimed in claim 2, wherein the fixing element (11) is a flexible rod (17) of a plastic which is provided with a ferromagnetic coating or which contains ferromagnetic components.
 4. The insert part as claimed in claim 2, wherein the fixing element (11) has a plastic tube (13) which forms an at least almost closed casing of the inner core (15) which has ferromagnetic properties.
 5. The insert part as claimed in claim 4, wherein the core is formed by a ferromagnetic wire (15).
 6. The insert part as claimed in claim 4, wherein the core is formed by a substance which contains ferromagnetic components and which is located within the plastic tube.
 7. The insert part as claimed in claim 2, wherein the fixing element (11) for the application of clamp-like anchoring elements extending behind it has a sequence of alternating longitudinal sections (7) which are kept clear of foam material and which are separated from each other by longitudinal sections (9) which are fixed in the foam material.
 8. The insert part as claimed in claim 7, wherein the longitudinal sections (7 and 9) of the fixing element (11) which are fixed in the foam material and which are kept clear of the foam material each have approximately the same length.
 9. The insert part as claimed in claim 7, wherein the fixing element (11) in the longitudinal sections (7) which are kept clear of foam material is provided with a foam-repellent coating.
 10. The insert part as claimed in claim 1, wherein the plastic jacket (13) is structured to increase its active surface. 